IOWA CITY, Iowa—A pilot was caught transporting a large shipment of high-grade marijuana from California to the east coast when his plane stopped at a rural Iowa airport for maintenance, according to a criminal complaint released Thursday.

Angelo P. Efthimiatos was the pilot of a small Piper aircraft that landed Tuesday morning at the municipal airport in Washington, Iowa, where he hoped to refuel and have workers inspect a mechanical problem, according to the complaint.

The Department of Homeland Security Air and Marine Operations Center, which is based in California and tasked with combating drug smuggling, was monitoring the flight, and asked local police to inspect his pilot's license and other aircraft documents.

Efthimiatos claimed he would retrieve the documents from the plane, but said he could not find them after he looked in a briefcase, the complaint says. A trained police dog was brought in to sniff the air around the plane, and gave an alert indicating the presence of controlled substances, it says.

Investigators later found 55 pounds of high-grade marijuana during a search of the plane, which may have a street value of $220,000 or more, the complaint says.

After Homeland Security agents arrived at the airport, Efthimiatos admitted to them during an interview that he was transporting drugs from California to the eastern part of the country for the fourth of fifth time, the complaint says. Efthimiatos explained that others had loaded the marijuana onto the plane, and he was planning to use a car after he landed to transport the drugs to another location on the east coast, where it would be retrieved by someone else, the complaint says.

Efthimiatos made an initial court appearance at the federal courthouse Davenport on Wednesday, and was ordered jailed pending a hearing Monday. He is charged with conspiring to distribute marijuana and possession of marijuana with intent to distribute.

Efthimiatos did not enter a plea at the appearance, and a public defender appointed to represent him didn't immediately return a phone message. His age and address were not immediately available.